It was confirmed last month that the first population of the forestry pest, the Asian longhorn beetle (ALB), was found in Kent, UK. Forest Research scientists discovered this damaging native of Japan and China infesting around 20 trees, and are now surveying the area to find out the full extent of the infestation. The establishment of this beetle in the UK could be extremely damaging, costing the timber industry millions of pounds, not to mention habitat loss for native species; there is no question that this pest should be eradicated as soon as possible.

Asian long horn beetle. Copyright Kyle Ramirez

The Asian longhorn beetle or Anoplophora glabripennis is a wood boring species, which lays its eggs under the bark of hardwood tree trunks or branches. The larvae feed through the cambium and enter the woody tissue where they continue to feed and eventually pupate. The larval stage may last from 10-22 months depending on environmental conditions, and feeding results in extensive galleries, destroying the wood within. This feeding can also affect the vascular functioning of the tree and may even lead to tree death.

Susceptible species in the UK include sycamore, elm, willow, horse chestnut, birch and poplar, although many other hardwood species may also be affected.

The 10mm exit hole of the adult is the most distinctive feature observed on an infested tree, although sap and/or frass from this hole may also be observed. However these are usually found 1.5m above ground level so a small infestation may not be found unless regular monitoring is going on, such as in the case in Kent, where the beetle was first observed in 2009.

As a quarantine pest for Europe and North America, control measures involve destroying infested trees and those susceptible within a varying distance of the infested trees, this is an expensive technique since it involves the destruction of mature trees, but since the larvae live within the wood, it is essential to guarantee the health of the surrounding trees.

In 2007, Italy dealt with the outbreak of the ALB by removing the four infested trees and all susceptible trees within a 500m radius and replanted with non-susceptible species, this amounted to the destruction of over 300 trees. The area was monitored for four years after the initial control measures to ensure the successful eradication of the pest. A report produced by CABI in 2010, calculated the costs associated with this case and estimated that this swift action cost £33,950.

A pile of wood from an infested maple tree in the US.Copyright P. Douglass, J. Forman Orth and M. Bohne.

The ALB has been found several times in North America since its first detection in 1996 via wood packing material from China. It has been found in New York, Chicago, New Jersey and Massachusetts. Quarantine zones and control methods were set up to control the spread. As an example of later stage control the costs were estimated by the Animal and Plant Health Inspection Service (APHIS) to be £18.7 million per annum to deal with (Smith et al. 2009). If the ALB is left to establish in the UK, the estimated costs of eradication could be as high as £435 million in total (Williams et al 2010).

The costs of eradication at an early stage seem high; however they are likely to increase dramatically if the invasion is allowed to spread. In the UK, we have many non-native invasive species that are past the point of complete control; I only need to mention the American grey squirrel or Japanese knotweed to conjure images of widespread pests we have trouble controlling. Measures taken by Forest Research and Fera thus far are ensuring this pest persists no longer.